Field
The present disclosure relates generally to communication systems, and more particularly, to triggering a acknowledgement/negative acknowledgement for a plurality of data transmissions sent in a plurality of downlink subframes.
Background
Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.
These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example telecommunication standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP). LTE is designed to support mobile broadband access through improved spectral efficiency, lowered costs, and improved services using OFDMA on the downlink, SC-FDMA on the uplink, and multiple-input multiple-output (MIMO) antenna technology. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE technology. These improvements may also be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.
In advanced communications using either the licensed spectrum (e.g., LTE-A) or a listen-before-talk (LBT) frame in the unlicensed spectrum (e.g., LTE-U), downlink (DL) hybrid automatic repeat request (HARQ) feedback may be transmitted from a user equipment (UE) to an evolved Node B (eNB) in predetermined uplink (UL) subframes. In addition, the UE may send channel state information (CSI) to the eNB in either periodic or aperiodic reports. However, transmitting HARQ feedback and/or CSI in this manner may be unreliable at times.